Photosensitive polymer containing Si, Ge or Sn and resist composition comprising the same

ABSTRACT

A photosensitive polymer including a copolymer of an acrylate or methacrylate monomer having a group indicated by the following formula (I), a comonomer selected from a maleic anhydride monomer and a cyclic vinyl ether monomer, and a resist composition including the same.  
                 
 
     In the formula, R 1 , R 2 , R 3 , and R 4  are independently a hydrogen atom, a C 1 -C 4  alkyl group, a C 1 -C 4  alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′) 3 , M is Si, Ge, Sn, or OSi, and each R′ independently is a C 1 -C 4  alkyl group, a C 1 -C 4  alkoxy group, a phenyl group, or a phenoxy group.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a chemically amplified resistcomposition, and more particularly, to a photosensitive polymercontaining silicon and a resist composition comprising the same.

[0003] 2. Description of the Related Art

[0004] As processes for manufacturing semiconductor devices become morecomplicated and the integration density of semiconductor devicesincreases, the need to form finer patterns becomes more pronounced.Furthermore, to manufacture semiconductor memory devices having acapacity of 1 Gigabit or more, a pattern size having a design rule of0.2 μm or less is needed. Accordingly, there is a limitation in formingsuch a fine pattern using conventional photoresist materials using a KrFexcimer laser (248 nm). For this reason, a lithography technique using anew exposure light source, the ArF excimer laser (193 nm), has emerged.

[0005] However, a resist material suitable for use in lithography withthe ArF excimer laser causes many problems for practical use, comparedwith conventional resist materials. The most serious problem is thecollapse of patterns with respect to an increase in the aspect ratio.Therefore, patterns must be formed using resist layers having athickness of 4000 angstroms or less. Other problems associated with theArF resist include the transmittance of the polymer. The ArF resist hasinferior transmittance as compared to the KrF resist. This is anotherreason why the thickness of the ArF resist layer must be reduced.

[0006] Almost all well-known ArF resists have a resistance to dryetching that is equal or inferior to that of the KrF resist. Therefore,when an underlying layer is patterned by lithography using resistpatterns obtained from the conventional resist materials, a satisfactoryprofile cannot be obtained.

[0007] Recently, to solve the foregoing problems, a technique using abi-layer resist (BLR) has been suggested. In a process using BLR, thelithography is performed using a resist material containing silicon.Silicon atoms within the resist material are glassed in the form ofSiO_(X) during dry etching by O₂ plasma to form a cured layer, and thecured layer is used as an etching mask during a subsequent dry etchingprocess. Therefore, when the aspect ratio is large, resistance to dryetching is increased by the curing layer, so that it is easy to formpatterns, and collapse of patterns can also be prevented. As a result,patterns having a large aspect ratio can be formed with high resolvingpower.

[0008] The amount of silicon in a polymer is an important factor for aBLR. Generally, as the amount of silicon increases, the likelihood thatthere will be problems due to a reduction in the thermal stability ofthe resist layer and the wettability to a developer increases.Therefore, the polymer must contain the right amount of silicon for aBLR process, and development of a resist material having excellentthermal stability and wettability to a developer becomes a seriousrequirement.

SUMMARY OF THE INVENTION

[0009] It is a feature of the present invention to provide aphotosensitive polymer that has a sufficient silicon content, that has areduced manufacturing cost, and that provides excellent lithographycharacteristics when used as a resist material.

[0010] It is another feature of the present invention to provide aresist composition having a silicon content sufficient to be used as aBLR for ArF excimer laser lithography, and at the same time, hasexcellent thermal stability and wettability to a developer.

[0011] In accordance with one aspect of the present invention, there isprovided a photosensitive polymer comprising a copolymer includingacrylate or methacrylate monomer unit having a group indicated as thefollowing formula (I), and a maleic anhydride monomer unit,

[0012] wherein R₁, R₂, and R₃ are independently a hydrogen atom, a C₁-C₄alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, aphenoxy group, or —M(R′)₃, wherein M is Si, Ge, Sn, or OSi, and each R′independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenylgroup, or a phenoxy group.

[0013] In a more particular embodiment, the photosensitive polymercomprises a copolymer having the following structural formula (II):

[0014] wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, andR₇ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or—M(R′)₃, wherein M is Si, Ge, Sn or OSi, and each R′ independently is aC₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxygroup, and m/(m+n) is between about 0.2-0.9.

[0015] In another more particular embodiment, the photosensitive polymercomprises a copolymer having the following structural formula (III):

[0016] wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇,R₈, and R₉ are independently a hydrogen atom, a C₁-C₄ alkyl group, aC₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or—M(R′)₃, wherein M is Si, Ge, Sn or OSi, and each R′ independently is aC₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxygroup, and m/(m+n) is between about 0.2-0.9.

[0017] In a further more particular embodiment, the photosensitivepolymer comprises a copolymer having the following structural formula(IV):

[0018] wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇,R₈, R₉, R₁₀, and R₁₁ are independently a hydrogen atom, a C₁-C₄ alkylgroup, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxygroup, or —M(R′)₃, wherein M is Si, Ge, Sn or OSi, and each R′independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenylgroup, or a phenoxy group, and m/(m+n) is between about 0.2-0.9.

[0019] In accordance with another aspect of the present invention, thereis provided a photosensitive polymer comprising a terpolymer includingan acrylate or methacrylate monomer unit having a group indicated as thefollowing formula (I), a maleic anhydride monomer unit, and a cyclicvinyl ether monomer unit,

[0020] wherein R₁, R₂, and R₃ are independently a hydrogen atom, a C₁-C₄alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, aphenoxy group, or —M(R′)₃, wherein M is Si, Ge, Sn, or OSi, and each R′independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenylgroup, or a phenoxy group.

[0021] In a more particular embodiment, the photosensitive polymercomprises a terpolymer having the following structural formula (V):

[0022] wherein, R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆,and R₇ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or—M(R′)₃, wherein M is Si, Ge, Sn, or OSi, and each R′ independently is aC₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxygroup, k is an integer from 1 to 6, and m/(m+n) is between about0.2-0.9.

[0023] In another more particular embodiment, the photosensitive polymercomprises a terpolymer having the following structural formula (VI):

[0024] wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇,R₈, and R₉ are independently a hydrogen atom, a C₁-C₄ alkyl group, aC₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or—M(R′)₃, wherein M is Si, Ge, Sn, or OSi, and each R′ independently is aC₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxygroup, k is an integer from 1 to 6, and m/(m+n) is between about0.2-0.9.

[0025] In a further more particular embodiment, the photosensitivepolymer comprises a terpolymer having the following structural formula(VII):

[0026] wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇,R₈, R₉, R₁₀, and R₁₁ are independently a hydrogen atom, a C₁-C₄ alkylgroup, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxygroup, or —M(R′)₃, wherein M is Si, Ge, Sn or OSi, and each R′independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenylgroup, or a phenoxy group, k is an integer from 1 to 6, and m/(m+n) isbetween about 0.2-0.9.

[0027] In accordance with an additional aspect of the present invention,there is provided a resist composition comprising (a) a photosensitivepolymer and (b) a photoacid generator (PAG). The photosensitive polymercomprises a copolymer of (a-1) an acrylate or methacrylate monomerhaving a group indicated by the formula (I) and (a-2) a comonomerselected from the group consisting of a maleic anhydride monomer and acyclic vinyl ether monomer,

[0028] wherein R₁, R₂, and R₃ are independently a hydrogen atom, a C₁-C₄alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, aphenoxy group, or —M(R′)₃, wherein M is Si, Ge, Sn, or OSi, and each R′independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenylgroup, or a phenoxy group.

[0029] Particular embodiments of the photosensitive polymer comprised ina resist composition according to the present invention includephotosensitive polymers of formulas (II)-(VII) as described above.

DETAILED DESCRIPTION OF THE INVENTION

[0030] Korean Patent Application No. 00-75944, filed on Dec. 13, 2000,and entitled: “Photosensitive Polymer Containing Silicon and ResistComposition Comprising the Same,” is incorporated by reference herein inits entirety.

[0031] In particular embodiments of the resist composition according tothe present invention, the weight average molecular weight of thephotosensitive polymer is from about 3,000 to about 100,000.

[0032] Also, specific embodiments of the resist composition according tothe present invention include the photoacid generator (PAG) in an amountfrom about 1 to about 30 wt % based on the weight of the photosensitivepolymer. Preferably, the PAG is selected from the group consisting oftriarylsulfonium salts, diaryliodonium salts, sulfonates, and mixturesthereof. More preferably, the PAG is triphenylsulfonium triflate,triphenylsulfonium antimonate, diphenyliodonium triflate,diphenyliodonium antimonate, methoxydiphenyliodonium triflate,di-t-butyldiphenyliodonium triflate, 2,6-dinitrobenzyl sulfonates,pyrogallol tris(alkylsulfonates), N-hydroxysuccinimide triflate,norbornene dicarboximide triflate, triphenylsulfonium nonaflate,diphenyliodonium nonaflate, methoxydiphenyliodonium nonaflate,di-t-butyldiphenyliodonium nonaflate, N-hydroxysuccinimide nonaflate,norbornene dicarboximide nonaflate, triphenylsulfoniumperfluorobutanesulfonate, triphenylsulfonium perfluorooctanesulfonate(PFOS), triphenylsulfonium perfluorocamphorsulfonate, diphenyliodoniumPFOS, methoxydiphenyliodonium PFOS, di-t-butyldiphenyliodonium triflate,N-hydroxysuccinimide PFOS, norbornene dicarboximide PFOS, or a mixturethereof.

[0033] The resist composition according to the present invention mayfurther include an organic base. The organic base preferably iscontained in an amount of about 0.01 to about 2.0 wt % based on theweight of the photosensitive polymer. Preferably, the organic base is acompound composed of a tertiary amine compound or a mixture of at leasttwo tertiary amine compounds. More preferably, the organic base istriethylamine, triisobutylamine, triisooctylamine, triisodecylamine,diethanolamine, triethanolamine, or a mixture thereof.

[0034] More particular embodiments of the resist composition accordingto the present invention can further include a surfactant in an amountfrom about 30 to about 200 ppm.

[0035] Also, particular embodiments of the resist composition accordingto the present invention can further include a dissolution inhibitor inan amount from about 0.1 to about 50 wt % based on the weight of thephotosensitive polymer.

[0036] The photosensitive polymer according to the present inventioncontains an element such as Si, Ge or Sn in its protecting group, and amaleic anhydride monomer or a cyclic vinyl ether monomer occupying arelatively small part within the polymer as an adhesion promoter.Therefore, the photosensitive polymer according to the present inventioncan be manufactured at low cost, and the resist composition can providesufficient resistance to dry etching, and secure excellent thermalstability and wettability to a developing solution.

[0037] The present invention is further illustrated by the followingnon-limiting examples.

EXAMPLE 1

[0038] Synthesis of Copolymer

EXAMPLE 1-1

[0039] (R=a Hydrogen Atom)

[0040] 18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol) and 9.8 gmaleic anhydride (0.1 mol) are dissolved in an amount of tetrahydrofuran(THF), benzene, dioxane, or ethyl acetate from about 0.1 to about 3times based on the weight of all of the monomers. Next, a polymerizationinitiator, in particular 2,2′-azobisisobutyronitrile (AIBN) or dimethyl2,2′-azobisisobutyrate (V601), in an amount from about 0.1 to about 20mol % on the basis of the total moles of all monomers, is added to thesolution. Dissolved oxygen is extracted from the solution so obtained bydegassing, and purging is performed using nitrogen. The resultantsolution is polymerized at a temperature between about 50-90° C. for2-48 hours, diluted with THF, and precipitated with excess isopropanol,ether, hexane, or a mixture thereof. The precipitate is dissolved in THFagain, and precipitated twice with isopropanol, ether, hexane, or amixture thereof. The precipitate so obtained is filtered, and dried in avacuum oven at about 50° C. for about 24 hours.

[0041] The ratio of m and n in the copolymer having the above structurecan be controlled by controlling the amounts of the two monomers used assynthesis sources, that is the amounts of(2-trimethylsilyl-2-propyl)acrylate and maleic anhydride.

[0042] As a result of synthesizing the copolymer having the abovestructure by the described method, 80% yield was obtained.

EXAMPLE 1-2

[0043] (R═CH₃)

[0044] 20 g 2-trimethylsilyl-2-propyl methacrylate (0.1 mol) and 9.8 gmaleic anhydride (0.1 mol) are dissolved in an amount of THF, benzene,dioxane, or ethyl acetate from about 0.1 to about 3 times based on theweight of all of the monomers. Next, a polymerization initiator, inparticular AIBN or V601, in an amount from about 0.1 to about 20 mol %on the basis of the total moles of all monomers, is added to thesolution. Dissolved oxygen is extracted from the obtained solution bydegassing, and purging is performed using nitrogen. The solution soobtained is polymerized at a temperature between about 50-90° C. for2-48 hours, diluted with THF, and precipitated with excess isopropanol,ether, hexane, or a mixture thereof. The precipitate is dissolved in THFagain, and precipitated twice with isopropanol, ether, hexane, or acompound thereof. The obtained precipitate is filtered, and dried in avacuum oven at about 50° C. for about 24 hours.

[0045] As a result of synthesizing the copolymer having the abovestructure by the described method, 85% yield was obtained.

EXAMPLE 2

[0046] Synthesis of Copolymer

EXAMPLE 2-1

[0047] (R=a Hydrogen Atom)

[0048] 24.4 g 1,1-bis(trimethylsilyl)ethyl acrylate (0.1 mol) and 9.8 gmaleic anhydride (0.1 mol) are dissolved in an amount of THF, benzene,dioxane, or ethyl acetate from about 0.1 to about 3 times based on theweight of all of the monomers. Next, a polymerization initiator, inparticular AIBN or V601 in an amount from about 0.1 to about 20 mol % onthe basis of the total moles of all monomers, is added to the solution.Dissolved oxygen is extracted from the solution so obtained bydegassing, and purging is performed using nitrogen. The solution thusobtained is polymerized at a temperature between about 50-90° C. for2-48 hours, diluted with THF, and precipitated with excess isopropanol,ether, hexane, or a mixture thereof. The precipitate is dissolved in THFagain, and precipitated twice with isopropanol, ether, hexane, or amixture thereof. The precipitate thus obtained is filtered, and dried ina vacuum oven at about 50° C. for about 24 hours.

[0049] The ratio of m and n in the copolymer of the above structure canbe controlled by controlling the amounts of two monomers used assynthesis sources, that is 1,1-bis(trimethylsilyl)ethyl acrylate andmaleic anhydride.

[0050] As a result of synthesizing the copolymer having the abovestructure by the described method, 80% yield was obtained.

EXAMPLE 2-2

[0051] (R═CH₃)

[0052] 25.8 g 1,1-bis(trimethylsilyl)ethyl methacrylate (0.1 mol) and9.8 g maleic anhydride (0.1 mol) are dissolved in an amount of THF,benzene, dioxane, or ethyl acetate from about 0.1 to about 3 times basedon the weight of all of the monomers. Next, a polymerization initiator,in particular AIBN or V601, in an amount from about 0.1 to about 20 mol% on the basis of the total moles of all monomers, is added to thesolution. Dissolved oxygen is extracted from the solution so obtained bydegassing, and purging is performed using nitrogen. The solution thusobtained is polymerized at a temperature between about 50-90° C. for2-48 hours, diluted with THF, and precipitated with excess isopropanol,ether, hexane, or a mixture thereof. The precipitate is dissolved in THFagain, and precipitated twice with isopropanol, ether, hexane, or amixture thereof. The precipitate so obtained is filtered, and dried in avacuum oven at about 50° C. for about 24 hours.

[0053] As a result of synthesizing the copolymer having the abovestructure by the described method, 80% yield was obtained.

EXAMPLE 3

[0054] Synthesis of Copolymer

[0055] 30 g monomer (0.1 mol) expressed by the following formula and19.6 g maleic anhydride (0.2 mol) are dissolved in an amount of THF,benzene, dioxane, or ethyl acetate from about 0.1 to about 3 times basedon the weight of all the monomers.

[0056] Next, a polymerization initiator, in particular AIBN or V601, inan amount from about 0.1 to about 20 mol % on the basis of the totalmoles of all monomers, is added to the solution. Dissolved oxygen isextracted from the solution so obtained by degassing, and purging isperformed using nitrogen. The solution thus obtained is polymerized at atemperature between about 50-90° C. for 2-48 hours, diluted with THF,and precipitated with excess isopropanol, ether, hexane, or a mixturethereof. The precipitate is dissolved in THF again, and precipitatedtwice with isopropanol, ether, hexane, or a mixture thereof. Theprecipitate so obtained is filtered, and dried in a vacuum oven at about50° C. for about 24 hours.

[0057] The ratio of m and n in the copolymer of the above structure canbe controlled by controlling the amounts of two monomers used assynthesis sources.

[0058] As a result of synthesizing the copolymer having the abovestructure by the described method, 70% yield was obtained.

EXAMPLE 4

[0059] Synthesis of Copolymer

[0060] The copolymer having the above structure is synthesized by thesame method as Example 3 using 34.3 g monomer (0.1 mol) expressed by thefollowing formula and 19.6 g maleic anhydride (0.2 mol).

[0061] As a result of synthesizing the copolymer having the abovestructure by the described method, 65% yield was obtained.

EXAMPLE 5

[0062] Synthesis of Terpolymer

EXAMPLE 5-1

[0063] (R=a Hydrogen Atom)

[0064] 18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol), 9.8 g maleicanhydride (0.1 mol), and 8.4 g 3,4-dihydro-2H-pyran (0.1 mol) aredissolved in an amount of THF, benzene, dioxane, or ethyl acetate fromabout 0.1 to about 3 times based on the weight of all the monomers.Next, a polymerization initiator, in particular AIBN or V601, in anamount from about 0.1 to about 20 mol % on the basis of the total molesof all monomers, is added to the solution. Dissolved oxygen is extractedfrom the solution so obtained by degassing, and purging is performedusing nitrogen. The solution thus obtained is polymerized at atemperature between about 50-90° C. for 2-48 hours, diluted with THF,and precipitated with excess isopropanol, ether, hexane, or a mixturethereof. The precipitate is dissolved in THF again, and precipitatedtwice with isopropanol, ether, hexane, or a mixture thereof. Theprecipitate so obtained is filtered, and dried in a vacuum oven at about50° C. for about 24 hours.

[0065] The ratio of m and n in the terpolymer of the above structure canbe controlled by controlling the amounts of monomers used as synthesissources.

[0066] As a result of synthesizing the terpolymer having the abovestructure by the described method, 80% yield was obtained.

EXAMPLE 5-2

[0067] (R═CH₃)

[0068] The terpolymer is synthesized by the same method as Example 5-1using 20 g 2-trimethylsilyl-2-propyl methacrylate (0.1 mol) instead of18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol).

EXAMPLE 6

[0069] Synthesis of Terpolymer

EXAMPLE 6-1

[0070] (R=a Hydrogen Atom)

[0071] The desired terpolymer is synthesized by the same method asExample 5-1 using 24.4 g 1,1-bis(trimethylsilyl)ethyl acrylate (0.1mol), 9.8 g maleic anhydride (0.1 mol), and 8.4 g 3,4-dihydro-2H-pyran(0.1 mol).

[0072] As a result of synthesizing the terpolymer having the abovestructure by the described method, 80% yield was obtained.

EXAMPLE 6-2

[0073] (R═CH₃)

[0074] The desired terpolymer is synthesized by the same method asExample 5-1 using 25.8 g 1,1-bis(trimethylsilyl)ethyl methacrylate (0.1mol), 9.8 g maleic anhydride (0.1 mol), and 8.4 g 3,4-dihydro-2H-pyran(0.1 mol).

EXAMPLE 7

[0075] Synthesis of Terpolymer

EXAMPLE 7-1

[0076] (R=a Hydrogen Atom)

[0077] The desired terpolymer is synthesized by the same method asExample 5-1 using 18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 7 g 2,3-dihydrofuran (0.1 mol).

[0078] As a result of synthesizing the terpolymer having the abovestructure by the described method, 80% yield was obtained.

EXAMPLE 7-2

[0079] (R═CH₃)

[0080] The desired terpolymer is synthesized by the same method asExample 5-1 using 20 g 2-trimethylsilyl-2-propyl methacrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 7 g 2,3-dihydrofuran (0.1 mol).

EXAMPLE 8

[0081] Synthesis of Terpolymer

EXAMPLE 8-1

[0082] (R=a Hydrogen Atom)

[0083] The desired terpolymer is synthesized by the same method asExample 5-1 using 24.4 g 1,1-bis(trimethylsilyl)ethyl acrylate (0.1mol), 9.8 g maleic anhydride (0.1 mol), and 7 g 2,3-dihydrofuran (0.1mol).

EXAMPLE 8-2

[0084] (R═CH₃)

[0085] The desired terpolymer is synthesized by the same method asExample 5-1 using 25.8 g 1,1-bis(trimethylsilyl)ethyl methacrylate (0.1mol), 9.8 g maleic anhydride(0.1 mol), and 7 g 2,3-dihydrofuran (0.1mol).

EXAMPLE 9

[0086] Synthesis of Terpolymer

EXAMPLE 9-1

[0087] (R=a Hydrogen Atom)

[0088] The desired terpolymer is synthesized by the same method asExample 5-1 using 18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 12.8 g3,4-dihydro-2-ethoxy-2H-pyran (0.1 mol).

EXAMPLE 9-2

[0089] (R═CH₃)

[0090] The desired terpolymer is synthesized by the same method asExample 5-1 using 20 g 2-trimethylsilyl-2propyl methacrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 12.8 g3,4-dihydro-2-ethoxy-2H-pyran (0.1 mol).

EXAMPLE10

[0091] Synthesis of Terpolymer

EXAMPLE 10-1

[0092] (R=a Hydrogen Atom)

[0093] The desired terpolymer is synthesized by the same method asExample 5-1 using 18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 11.4 g3,4-dihydro-2-methoxy-2H-pyran (0.1 mol).

EXAMPLE 10-2

[0094] (R═CH₃)

[0095] The desired terpolymer is synthesized by the same method asExample 5-1 using 20 g 2-trimethylsilyl-2-propyl methacrylate (0.1 mol),9.8 maleic anhydride (0.1 mol), and 11.4 g3,4-dihydro-2-methoxy-2H-pyran (0.1 mol).

EXAMPLE 11

[0096] Synthesis of Terpolymer

EXAMPLE 11-1

[0097] (R=a Hydrogen Atom)

[0098] The desired terpolymer is synthesized by the same method asExample 5-1 using 18.6 g 2-trimethylsilyl-2-propyl acrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 11.4 g5,6-dihydro-4-methoxy-2H-pyran (0.1 mol).

EXAMPLE 11-2

[0099] (R═CH₃)

[0100] The desired terpolymer is synthesized by the same method asExample 5-1 using 20 g 2-trimethylsilyl-2-propyl methacrylate (0.1 mol),9.8 g maleic anhydride (0.1 mol), and 11.4 g5,6-dihydro-4-methoxy-2H-pyran (0.1 mol).

EXAMPLE 12

[0101] Synthesis of Terpolymer

[0102] The desired terpolymer is synthesized by the same method asExample 5-1 using 30 g monomer of the structure illustrated in Example 3(0.1 mol), 9.8 g maleic anhydride (0.1 mol), and 7 g 2,3-dihydrofuran(0.1 mol).

[0103] As a result of synthesizing the terpolymer having the abovestructure by the described method, 70% yield was obtained.

EXAMPLE 13

[0104] Synthesis of Terpolymer

[0105] The desired terpolymer is synthesized by the same method asExample 5-1 using 34.3 g monomer of the structure illustrated in Example4 (0.1 mol), 9.8 g maleic anhydride (0.1 mol), and 7 g 2,3-dihydrofuran(0.1 mol).

[0106] As a result of synthesizing the terpolymer having the structureby the described method, 66% yield was obtained.

EXAMPLE 14

[0107] Lithography Performance

[0108] The polymers (1.0 g) obtained in Examples 1 through 13 aredissolved in a propylene glycol monomethyl ether acetate (PGMEA) (8.0 g)solution with a photoacid generator (PAG), 0.01- 0.03 gtriphenylsulfonium trifluoromethansulfonate (triflate), and an organicbase, 2 mg triisobutylamine, respectively, and filtered using a 0.2 μmmembrane filter, so that respective resist compositions are obtained.The resist compositions are coated on Si wafers treated by organicanti-reflective coating (ARC) to a thickness of about 0.1-0.3 μm.

[0109] Next, the respective wafers coated with the resist compositionsare soft-baked at a temperature between about 120-130° C. for about 90seconds, exposed using an ArF or KrF excimer laser stepper, andpost-exposure baked (PEB) at a temperature of about 120° C. for about 90seconds. Next, the wafers are developed using a 2.38 wt %tetramethylammonium hydroxide (TMAH) solution for about 60 seconds toform resist patterns.

[0110] Patterns are transcribed in an underlying layer with O₂-RIE(reactive ion etch) using the obtained resist patterns.

[0111] In the above description, after the resist layers are developedusing a developer, and the resist patterns are formed, patterns aretranscribed in an underlying layer by O₂-RIE. However, it is possible totranscribe patterns in an underlying layer by omitting the step ofdeveloping with a developer and directly applying O₂-RIE to a latentimage after performing PEB.

[0112] Also, in the above description, between about 0.01-0.03gtriphenylsulfonium triflate is used as the PAG, but any materialconventionally used as a PAG can be used. For example, between about0.01-0.06 g triphenylsulfonium perfluorobutanesulfonate,triphenylsulfonium perfluorooctanesulfonate, or triphenylsulfoniumperfluorocamphorsulfonate can be used.

[0113] A photosensitive polymer according to the present inventioncontains an element such as Si, Ge, or Sn in its protecting group. Whenpatterns are formed using a resist composition comprising such aphotosensitive polymer, the protecting group is removed by acidgenerated by far-ultraviolet rays such as KrF or ArF, and by PEB.Therefore, the content of the element such as Si, Ge, or Sn becomesdifferent in an exposure portion and a non-exposure portion, and at thesame time, solubility to an alkali solvent becomes different. Then, thelatent image is etched using O₂-RIE, or the latent image is developedwith an alkali solution, and patterned, and the underlying layer thenetched using O₂-RIE. Here, an oxide layer which is composed of SiO_(x)is formed in the non-exposure portion where Si, Ge or Sn exists amongthe resist layers during dry etching, and such an oxide layer does notexist in the exposure portion. Therefore, the underlying layer formedof, for example, a reflection preventing layer, can be patterned using adifference in the selectivity to O₂-RIE in the non-exposure portion andthe exposure portion.

[0114] Also, the photosensitive polymer according to the presentinvention includes an acrylate or methacrylate monomer unit containingSi, Ge, or Sn, and a maleic anhydride monomer unit or a cyclic vinylether monomer unit acting as an adhesion promoter. Here, since the sizeof the portion acting as an adhesion promoter within a polymer isrelatively very small, the portion of Si, Ge, or Sn among the wholestructure of the polymer becomes relatively larger. Therefore, superiorselectivity can be provided as compared to conventional materials. Also,the maleic anhydride monomer and vinyl ether monomer are very cheap.Therefore, the photosensitive polymer according to the present inventioncan be manufactured at low cost, and the resist composition can providesufficient resistance to dry etching, and secure excellent thermalstability and wettability to a developer.

[0115] While this invention has been particularly shown and describedwith reference to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A photosensitive polymer including a copolymer combined with an acrylate or methacrylate monomer unit having a group indicated as the following formula (I), and a maleic anhydride monomer unit,

wherein R₁, R₂, and R₃ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn, or OSi, and each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group.
 2. The photosensitive polymer of claim 1 comprising a copolymer having the following structural formula (II)

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, and R₇ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, and m/(m+n) is from about 0.2 to about 0.9.
 3. The photosensitive polymer of claim 1 comprising a copolymer having the following structural formula (III)

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇, R₈, and R₉ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, and m/(m+n) is from about 0.2 to about 0.9.
 4. The photosensitive polymer of claim 1 comprising a copolymer having the following structural formula (IV)

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl groups, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, and m/(m+n) is from about 0.2 to about 0.9.
 5. A photosensitive polymer comprising a terpolymer including an acrylate or methacrylate monomer unit having a group indicated by the following formula (I), a maleic anhydride monomer unit, and a cyclic vinyl ether monomer unit,

wherein R₁, R₂, and R₃ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn, or OSi, and each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group.
 6. The photosensitive polymer of claim 5 comprising a terpolymer having the following structural formula (V)

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, and R₇ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn, or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, k is an integer from 1 to 6, and m/(m+n) is from about 0.2 to about 0.9.
 7. The photosensitive polymer of claim 5 comprising a terpolymer having the following structural formula (VI)

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇, R₈, and R₉ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn, or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, k is an integer from 1 to 6, and m/(m+n) is from about 0.2 to about 0.9.
 8. The photosensitive polymer of claim 5 comprising a terpolymer having the following structural formula (VII)

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or M(R′)₃, M is Si, Ge, Sn or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, k is an integer from 1 to 6, m/(m+n) is from about 0.2 to about 0.9.
 9. A resist composition comprising: (a) a photosensitive polymer comprising a copolymer of: (a-1) an acrylate or methacrylate monomer having a group indicated by the following formula (I)

wherein R₁, R₂, and R₃ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn, or OSi, and each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, and (a-2) a comonomer selected from the group consisting of a maleic anhydride monomer and a cyclic vinyl ether monomer, and (b) a photoacid generator (PAG).
 10. The resist composition of claim 9, wherein the comonomer includes a maleic anhydride monomer, and the photosensitive polymer has one structure selected from the following structures (II) to (IV):

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R5, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl groups, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn, or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, and m/(m+n) is between about 0.2 to about 0.9.
 11. The resist composition of claim 9, wherein the comonomer includes a maleic anhydride monomer and a cyclic vinyl ether monomer, and the photosensitive polymer has one structure selected from the following structures (V) to (VII):

wherein R₄ is a hydrogen atom or a C₁-C₄ alkyl group, R₅, R₆, R₇, R₈, R₉, R₁₀, and R₁₁ are independently a hydrogen atom, a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, a benzyl group, a phenoxy group, or —M(R′)₃, M is Si, Ge, Sn or OSi, each R′ independently is a C₁-C₄ alkyl group, a C₁-C₄ alkoxy group, a phenyl group, or a phenoxy group, k is an integer from 1 to 6, and m/(m+n) is between about 0.2 to about 0.9.
 12. The resist composition of claim 9, wherein the weight average molecular weight of the photosensitive polymer is between about 3,000 to about 100,000.
 13. The resist composition of claim 9, wherein the PAG is contained in an amount from about 1 to about 30 wt % based on the weight of the photosensitive polymer.
 14. The resist composition of claim 9, wherein the PAG is selected from the group consisting of triarylsulfonium salts, diaryliodonium salts, sulfonates, and mixtures thereof.
 15. The resist composition of claim 9, further comprising an organic base.
 16. The resist composition of claim 15, wherein the organic base is contained in an amount from about 0.01 to about 2.0 wt % based on the weight of the photosensitive polymer.
 17. The resist composition of claim 15, wherein the organic base is a tertiary amine compound or a mixture of at least two tertiary amine compounds.
 18. The resist composition of claim 17, wherein the organic base is triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, diethanolamine, triethanolamine, or a mixture of thereof.
 19. The resist composition of claim 9, further comprising a surfactant in an amount from about 30 to about 200 ppm.
 20. The resist composition of claim 9, further comprising a dissolution inhibitor in an amount from about 0.1 to about 50 wt % based on the weight of the photosensitive polymer. 